Diet is huge. Also, don't work the same muscle groups 2 days in a row. You need at least 24 hours rest in between. The workout tears down your muscle, rest rebuilds it. It also depends on your goals. If you are looking to lose weight, then you want to work up to 30 min of cardio 5x weekly. If not, you can improve your cardio fitness with 20-30 min 3x weekly.
yeah cardio is important, and don't spend more than an hour doing weights.
give yourself different day's to work out different muscle groups
also go get whey protein that you can mix in with Milk, it taste a bit nasty but it's all protein and helps form muscle. now theres a certain way to take protein it's measured in some form, speak to a nuetirtionist(sp) about that.
and theres other form's of protein, Steak,Egg's,Chicken (take off the skin)
my routine used to be 1 hour weights, 45 minutes cardio, and now the only thing I eat is either subway or something home made.
if your looking to "loose weight", drink what's "fuze" they have Super Citirmax, Vitiam B6 B12, etc. loads of stuff I can't remembe I just had one a minute ago, it makes you poop but lol it cleasnes your system.